Preparation and characterization of nanometer-sized (Pb1−x,Bax)TiO3 powders using acetylacetone as a chelating agent in a non-aqueous sol–gel process

(1)

Preparation

and

characterization

of

nanometer-sized

(Pb

1 x

,Ba

x

)TiO

3

powders

using

acetylacetone

as

a

chelating

agent

in

a

non-aqueous

sol–gel

process

Hong

Zhu

a

,

Zhijun

Guo

b

,

Wein-Duo

Yang

c,

*

,

Wein-Feng

Chang

c

,

Cheng-Chin

Wang

c

a

InstituteofModernCatalysis,DepartmentofOrganicChemistry,StatekeyLaboratoryofChemicalResourceEngineering, BeijingUniversityofChemicalTechnology,Beijing100029,PRChina

b

SchoolofScience,BeijingJiaotongUniversity,Beijing100044,PRChina c

DepartmentofChemicalandMaterialsEngineering,NationalKaohsiungUniversityofAppliedSciences,Kaohsiung807,Taiwan Received30August2010;receivedinrevisedform18January2011;accepted22March2011

Availableonline27May2011

Abstract

Nanometer-sized

lead

barium

titanate

(Pb

1 x

Ba

x

TiO

3

,

PB

x

T)

powders

were

prepared

by

a

non-aqueous

sol–gel

process

using

lead

acetate,

barium

acetate,

and

titanium

isopropoxide

as

precursors

and

ethylene

glycol

as

the

solvent.

In

this

procedure,

Ti-isopropoxide

was

chelated

with

acetylacetone.

The

samples

were

characterized

by

Fourier

transform

infrared

spectroscopy

(FTIR),

Raman

spectroscopy,

thermogravimetric

analysis/differential

thermal

analysis

(TGA/DTA),

X-ray

diffraction

(XRD),

scanning

electron

microscopy

(SEM)

and

Brunauer–Emmett–Teller

(BET)

specific

surface

area

analysis.

The

results

indicate

that

perovskite

PB

x

T

phases

were

obtained

by

heat

treatment

at

450 8C

for

5 h,

and

a

pure

perovskite

was

examined

at

600 8C.

The

average

particle

sizes

of

perovskite

PB

x

T

powders

calcined

at

600 8C

were

approximately

about

40–

80 nm,

and

BET

analysis

showed

that

the

surface

areas

of

the

powders

obtained

at

600 8C

were

approximately

6–16

m

2

_/g.

_In

_addition,

_the

_phase

transition

from

the

tetragonal

ferroelectric

phase

to

the

cubic

paraelectric

phase

occurred

in

a

range

of

approximately

0.6 <

x

<

0.8. #

₂₀₁₁

_Published

_by

_Elsevier

_Ltd

_and

_Techna

_Group

_S.r.l.

Keywords:Nanometer-sized;Leadbariumtitanate;Non-aqueous;Sol–gelprocess

1. Introduction

The

sol–gel

method

involving

hydrolysis

and

polyconden-sation,

gelation,

aging,

drying

and

heat

treatment

results

in

homogeneous

distributed

particles

with

high

purity

and

controlled

chemical

composition

[1,2]

.

It

is

important

that

the

sol–gel

synthesis

is

carried

out

at

a

low

temperature.

Solid

solutions

of

lead

barium

titanate

with

excellent

dielectric

[3]

,

piezoelectric

[4]

,

pyroelectric

[5]

,

ferroelectric

[6]

and

optical

properties

[7]

are

used

in

many

electronic

and

optical

devices,

including

non-volatile

random

access

mem-ories,

infrared

sensors

and

actuators.

The

compatibility

of

the

starting

materials

is

important

to

form

a

stable

precursor

solution

in

the

multicomponent

system.

Ti

alkoxides

are

more

moisture-sensitive,

and

therefore,

some

chemical

agents

are

added

to

stabilize

the

Ti

precursor

[8–

10]

.

Using

acetylacetone

as

a

chelating

agent

with

metal

alkoxide

can

affect

the

hydrolysis

of

the

starting

materials

to

produce

new

precursors

[6,11]

.

However,

the

metal-organic

precursor

chelated

with

acetylacetone

is

no

longer

moisture-sensitive

[12]

.

In

our

work,

acetylacetone-chelated

Ti

isopropoxide

at

a

molar

ratio

of

1:4

produced

modified

metal-organic

precursors

with

better

uniformity,

and

the

PBT

powder

obtained

possessed

better

mechanical

properties

and

lower

synthesis

temperature

[13]

.

Some

research

results

on

Pb

1 x

Ba

x

TiO

3

thin

films,

powders

and

ceramics

by

sol–gel

processing

are

available

in

the

literature

[14,15,12]

.

The

Pb

1 x

Ba

x

TiO

3

system

has

not

been

thoroughly

studied.

In

this

paper,

Pb

1 x

Ba

x

TiO

3

powders

were

prepared

by

a

non-aqueous

sol–gel

route

and

characterized

in

detail.

Moisture-free

Pb

1 x

Ba

x

TiO

3

sols

were

obtained

by

mixing

Ti

isopropoxide

chelated

with

acetylacetone

and

an

ethylene

glycol

solution

dissolved

with

lead

acetate

tri-hydrate

www.elsevier.com/locate/ceramint

Available online at www.sciencedirect.com

CeramicsInternational37(2011)3203–3209

*Correspondingauthor.

E-mailaddress:[email protected](W.-D.Yang).

0272-8842/$36.00#₂₀₁₁_Published_by_Elsevier_Ltd_and_Techna_Group_S.r.l. doi:10.1016/j.ceramint.2011.05.090

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4. Conclusions

Nanometer-sized

Pb

1 x

Ba

x

TiO

3

powders

were

prepared

by

a

non-aqueous

sol–gel

process

with

acetylacetone

as

a

chelating

agent

and

ethylene

glycol

as

a

solvent.

In

the

sol–gel

process,

the

hydrolysis

reaction

was

significantly

strengthened

and

the

polycondensation

reaction

was

weakened

upon

increasing

the

barium

content,

which

crosslinked

the

network

gel

cracked

at

lower

temperatures.

The

crystallization

of

the

PB

0.4

T

per-ovskite

structure

occurred

at

temperatures

as

low

as

450 8C,

and

a

pure

perovskite

phase

was

obtained

upon

calcination

at

600 8C.

The

average

particle

sizes

of

PB

x

T

powders

heat-treat

at

600 8C

were

approximately

40–80

nm.

The

surface

areas

of

the

powders

ranged

from

6.3 m

2

/g

to

16.6 m

2

/g.

In

addition,

the

phase

transition

from

the

tetragonal

ferroelectric

phase

to

the

cubic

paraelectric

phase

occurred

at

0.6 <

x

<

0.8. Acknowledgement

The

authors

gratefully

acknowledge

the

financial

support

of

the

National

Science

Council

of

the

Republic

of

China

(Taiwan).

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